The Colosseum was Rome’s entertainment hotspot. It hosted an array of events from gladiator battles, staged naval battles, and hunts. Similar to modern MMA or boxing, gladiators were categorized by weight class, experience, and fighting style. The stadium could seat between 50-80,000 spectators, eager to watch the displays.
All historic evidence is just stories. So, just because you don't know of it doesn't mean it doesn't exist...